Age of Information: A Two-Sensor Status Update System Monitoring The Same Process

TL;DR

This paper analyzes the average age of information in a two-sensor monitoring system, modeling it as parallel queues and deriving formulas for AoI, which helps understand how redundant sensors affect information freshness.

Contribution

It introduces a stochastic hybrid system approach to analyze AoI in a two-sensor system, providing a closed-form solution for symmetric sensor parameters.

Findings

Validated the theoretical AoI formulas with numerical results.

Demonstrated that redundant sensors can improve information freshness.

Provided a general analytical framework for AoI in multi-sensor systems.

Abstract

This work studies the average age of information (AoI) of a monitoring system in which two sensors are sensing the same physical process and update status to a common monitor using their dedicated channels. Generally, using redundant devices to update the status of a process can improve the information timeliness at the monitor, but the disordered arrivals of updates also make the AoI analysis challenging. To that end, we model the system as two M/M/1/1 parallel status updating queues. By leveraging tools from stochastic hybrid system (SHS), we provide a general approach to analyze the average AoI, whereas a closed-form expression can be obtained when the status arrival rates and/or the service rates are the same for the two sensors. Numerical results validate the correctness of the theoretical analysis.